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Up Topic Welding Industry / Technical Discussions / question about slip on flanges
- - By dlmann (**) Date 04-08-2011 03:51 Edited 04-08-2011 04:20
I've got troubles concerning this slip-on flange.  Can this work?  Its slipped it over the end of a reducer, so there won't be a fillet on the outside.  I want to reject it on the basis of not comforming with ASME B31.3, Fig. 328.5.2B Typical Details for Double-Welded Slip-On and Socket Welding Flange Attachment. 

Now para 328.5.2 says  "If slip-on flanges are single welded, the weld shall be at the hub."  Does "at the hub" mean inside or outside of the flange?

Is this configuration as shown compliant with anything (B31.3 or otherwise)? 

Thanks in advance, Donnie Mann
Attachment: sliponflange.JPG (490k)
Parent - By MBSims (****) Date 04-08-2011 13:46
Donnie,

The hub is on the outside.  It sounds like it does not meet para. 328.5.2.  If the drawing only shows a weld on the inside, perhaps an RFI to the engineer requesting clarification is needed.  A short piece of pipe welded to the reducer would make this right.
Parent - By G.S.Crisi (****) Date 04-08-2011 17:10
The problem of the piece of pipe suggested by Marty is that the piece could be too short.
If I were you I'd use a welding neck flange and that's it.
Giovanni S. Crisi
Sao Paulo - Brazil
- - By qcrobert (***) Date 04-08-2011 14:52
True, the hub of a flange is the raised thick portion on the outside of the flange.

However I do not see the problem of welding both sides of a SO flange to either end of a reducer fitting.
Parent - By Jim Hughes (***) Date 04-09-2011 15:03
Robert,
That was going to be my question, "why can't you weld it on both sides? If it can be welded on both sides then your issue is resolved.

Thanks
Jim
Parent - - By dlmann (**) Date 04-12-2011 14:13
Thanks to all for responding, you’ve helped me figure some of this out.  I realize just because I haven’t seen it here in my plant doesn’t mean it can't be done.   I would send a RFI to the engineer but he is going to go with whatever QA say he can do/get away with.  Not perfect but sometimes that is the way it is. 

I can't see where it is OK to put a reducer into a slip on flange, even if it’s welded on both sides.  How is this supported by the code?  I've looked in B31.3 and this configuration doesn’t conform to ASME B31.3, Fig. 328.5.2B Typical Details for Double-Welded Slip-On and Socket Welding Flange Attachment. 
I've suggested a weld neck flange for this application.
Parent - By RANDER (***) Date 04-12-2011 16:06
I agree that the configuration you describe may not be typical.  I have not seen it in the field either but it may be done somewhere.  There may be a mistake in the drawing so your RFI to the engineer is the proper course of action.  At a minimum it will show your concerns, recommendations and  it may help you in the future no matter what the engineer decides to do.
Parent - - By qcrobert (***) Date 04-15-2011 16:57
From an engineering point of view, what argument do you propose that an ANSI/ASME B16.5, BS 1560 or API Spec 6A slip on flange to reducer (either end) to be not acceptable?

Thermal expansion, allowable stress factors, joint effeciency are not compromised by this type of joint.

This is commonly used when space limitations are considered but can be used without any consideration for space.

As far as B31.3 is concerned, it presents typical details for slip on flanges and does not attempt to address all details to be encountered in construction P&IDs.

The "Code" or any other ASME code does not attempt to "support" and (excerpt from Foreword) "is not a handbook, and cannot substitute for education, experience and sound engineering judgment."

I do admire your consideration on this issue and concurr that an RFI to the engineer is generated and logged in your book.

My past experience has taught me that RFIs and Request for Deviations to the PE brought needed attention to the issue at hand.

Keep us informed and good luck to ya,
QCRobert
Parent - - By G.S.Crisi (****) Date 04-15-2011 18:46
qc,
1st. question: are BS (British Standards) still used? I thought that all nationals standards in Europe (BS, DIN, Afnor, SIS, UNI etc) had been replaced by ISO.

2nd question: what does RFI mean?

Thanks for the answer.
Giovanni S. Crisi
Parent - By 803056 (*****) Date 04-15-2011 18:59
"Request For Information," i.e., it is a request made to the engineer for clarification about "something."

Best regards - Al
Parent - - By qcrobert (***) Date 04-20-2011 18:16
1.  Back in March 2010, the national standard institutions within the EU and European Free Trade Association were obliged to withdraw all national standards that conflict with the European Committee of Standardization’s suite of structural Eurocodes.

In Britain BS I will withdraw 57 national standards, including all or most parts of wellknown codes such as BS 5400 for bridges, BS 5950 for steel, BS 8004 for foundations, etc.

April 2010, the national codes of practice for the design of buildings and civil engineering works in the UK be the 58 parts of the ten new BS EN Eurocodes.

ISO Standards are in place but have not entirely replaced the BS EN Eurocodes.

2.  Request For Info
Parent - By joe pirie (***) Date 04-26-2011 17:39
i've welded countless slip on flanges to reducers, 90's tees etc. If i remember correct  you can't use slip on flanges on type M pipe systyems under ASME  B31.3  
depends what code your welding to whether  its allowed or not  Joe
Parent - - By Jim Hughes (***) Date 05-16-2011 11:53
Because the key word is typical. It also say's not every configuration is addressed. I gues I am a little confused about why you think welding slip on flanges on a reducer is a problem? Its a piece of pipe. My second question and it's something I and you should be concerned about, and that is your engineering group deferring to QC about a design issue. Sounds to me like you don't really have an engineering group.

Jim
Parent - - By ssbn727 (*****) Date 05-19-2011 13:52
Good point there Jim.

Respectfully,
Henry
Parent - By Jim Hughes (***) Date 05-21-2011 15:08
Thanks Henry.

Jim
- By youngaaron Date 05-10-2011 21:06
does anyone have a standard procedure for cast iron using chromacast 211
Up Topic Welding Industry / Technical Discussions / question about slip on flanges

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